1. Field of the Invention
This invention relates to metallic tow or metallic threads and more particularly to an apparatus and method of producing high quality metallic mesh from an array of metallic threads made from fine metallic fibers.
2. Description of the Related Art
This invention relates to metallic mesh or metallic fiber cord and more particularly to an improved apparatus and method of producing high quality metallic mesh or metallic fabric from an array of fine metallic fibers. Metallic mesh is generally formed from a matrix of metallic fiber tow or continuous metallic cord. The metallic fiber tow or continuous metallic cord is characterized as an array of parallel metallic fibers forming a continuous cord of a suitable length. Typically, each of the metallic fibers of the mesh is less than 50 microns in diameter. The metallic fiber tow normally includes continuous metallic fibers in a quantity greater than 19 parallel metallic fibers.
The production of high quality metallic fiber tow is a more difficult task than the production of high quality chopped metallic fibers. Typically, chopped metallic fibers have a length of less than 2 to 3 centimeters. Both metallic fiber tow and metallic chopped fibers are formed in a similar manner. The metallic fibers are formed by cladding an array of metallic wires and drawing the clad array to reduce the outer diameter thereof and to reduce the corresponding diameters of the array of metallic wires thereby producing an array of metallic fibers. The clad array of metallic fibers is chopped into cladding sections of less than two to three centimeters. The chopped cladding sections are placed into a leaching bath to remove the cladding material thereby producing chopped metallic fibers.
The metallic fiber tow is a more difficult task to produce than chopped metallic fibers since clad metallic fiber tow is more difficult to leach than chopped clad metallic fibers. The metallic fiber tow is made in a similar fashion with the exception that the continuous cladding of continuous metallic fibers must be leached as a continuous cladding of metallic fiber tow. The prior art has utilized two methods of leaching the continuous cladding of metallic fiber tow, namely the continuous leaching process and the batch leaching process. In the continuous leaching process, the continuous cladding of metallic fiber tow is passed through a longitudinally extending leaching bath thereby giving a chemical agent sufficient time to remove the cladding material leaving the continuous metallic fiber tow. This process necessitated the use of a long leaching bath, which was unsatisfactory in many cases. Secondly, the continuous cladding of metallic fiber tow had to be pulled through the longitudinally extending leaching tank thereby placing substantial stress on the metallic fiber tow after removal of the cladding material. This substantial stress on the metallic fiber tow resulted in breakage of some of the metallic fibers in the metallic fiber tow thereby reducing the quality thereof.
The second method of leaching the continuous cladding of metallic fiber tow was through a batch process. In the batch process, the continuous cladding of metallic fiber tow was reeled onto a leaching spool and placed in a leaching bath. In order to prevent the individual metallic fibers of one winding of the metallic fiber tow from being entangled with individual metallic fibers of an adjacent winding the continuous cladding of metallic fiber tow was twisted as the continuous cladding of metallic fiber tow was reeled onto the leaching spool.
After the batch leaching process, the continuous cladding of metallic fiber tow was unreeled from the leaching spool and placed on a transport spool or for ultimate use. Unfortunately, the twisting of the continuous metallic fiber tow did not totally prevent the individual metallic fibers of one winding of the metallic fiber tow from being entangled with individual metallic fibers of an adjacent winding of the continuous metallic fiber tow. Accordingly, the unreeling of the continuous metallic fiber tow from the leaching spool resulted in breakage of some of the individual metallic fibers thereby providing poor quality fiber tow.
In some instances, the continuous metallic fiber tow was used in the production of high quality metallic mesh. Many processes have been known in the prior art for the manufacture and production of high quality metallic mesh. Among the prior art that have attempted to provide for the manufacturing and production of high quality metallic fiber tow and/or high quality metallic mesh are the following United States patents.
U.S. Pat. No. 2,050,298 to Everett discloses a process for the production of stranded wire by reduction from elements of comparatively large cross-sections. The process comprises the steps of assembling of a plurality of the elements in side-by-side relationship. The encased assembly of elements is reduced thus formed as a unit and imparting a permanent helical twist to the reduced bundle and then removing the casing.
U.S. Pat. No. 3,505,039 to Roberts et al. discloses a product defined as fine metal filaments, such as filaments of under approximately 15 microns diameter, in long lengths wherein a plurality of sheathed elements are first constricted to form a reduced diameter billet by means of hot forming. After the hot forming constriction, the billet is then drawn to the final size wherein the filaments have the desired final small diameter. The material surrounding the filaments is then removed by suitable means leaving the filaments in the form of a tow.
U.S. Pat. No. 3,540,114 to Roberts et al. discloses a method of forming fine filaments formed of a material such as metal by multiple end drawing a plurality of elongated elements having thereon a thin film of lubricant material. The plurality of elements may be bundled in a tubular sheath formed of drawable material. The lubricant may be applied to the individual elements prior to the bundling thereof and may be provided by applying the lubricant to the elements while they are being individually drawn through a coating mechanism such as a drawing die. The lubricant comprises a material capable of forming a film having a high tenacity characteristic whereby the film is maintained under the extreme pressure conditions of drawing process. Upon completion of the constricting operation, the tubular sheath is removed. If desired, the lubricant may be also removed from the resultant filaments.
U.S. Pat. No. 3,698,863 to Roberts et al. discloses a metallic filament that has an effective diameter of less than 50 microns and is formed while surrounded by a subsequently removed sacrificial matrix. The filament has a preselected peripheral surface varying from substantially smooth to re-entrant and a preselected surface to volume ratio. The area of the filament also has a controlled non-uniformity along the length thereof which provides an acceptable dimensional tolerance. The metallic filament may be substantially one metal, bimetallic or tubular.
U.S. Pat. No. 3,977,069 to Domaingue, Jr. discloses that this invention contemplates a method and apparatus for taking fine metal fibers having a diameter range from 0.5 microns to approximately 150 microns and cutting the fibers into precise short lengths. The method and apparatus comprises first moistening tows of metal fibers and unwinding the tows from spools and positioning them into tow bands. A stiffened ribbon made from the tow bands is cut to the desired precise lengths in order to prevent cold welding or deformation of the ends of the fibers during the cutting operation. Materials that may be used for stiffening the fibers include starch, PCA, ice, etc.
U.S. Pat. No. 3,977,070 to Schildbach discloses the method of forming a tow of filaments wherein a bundle of elongated elements such as rods or wires, is clad by forming a sheath of material different from that of the elements about the bundle. The bundle is subsequently drawn to constrict the elements to a desired small diameter. The elements may be formed of metal. The bundle may be annealed, or stress relived, between drawing steps as desired. The sheath may be formed of metal and may have juxtaposed edges thereof welded together to retain the assembly. The sheath is removed from the final constricted bundle to free the filaments in the form of tow.
U.S. Pat. No. 4,010,004 to Brown et al. discloses a metallic velvet material comprising a woven textile pile fabric wherein at least a portion of the woven base fabric and/or the velvet surface-forming pile yarns is metallic. The metallic yam may comprise a blended yarn formed of staple metal fibers and conventional nonmetallic textile fibers, or may be formed of continuous metal filament material. The metal fibers, or filaments, are preferably formed with rough unmachined and unburnished, fracture-free outer surfaces for improved retention in the velvet pile fabric.
U.S. Pat. No. 4,109,709 to Honda et al. discloses heat pipes comprising an outer tubular material closed at both ends. A wick of metal fibers covering an inner tubular material is inserted in the outer tubular material. A heat transfer volatile liquid is confined in the closed outer tubular material. An evaporation region and a condensing region are respectively constituted in the end portions of the outer tubular material. The liquid in the evaporation region vaporizes when heated and the vapor is passed to the condensing region to condense while giving the heat of the vapor to other materials outside the heat pipe. The condensed liquid is returned to the evaporation region by the capillary action of the wick, thus repeating a cycle of the evaporation and condensation.
U.S. Pat. No. 4,118,845 to Schildbach discloses the method of forming a tow of filaments and the tow wherein a bundle of elongated elements such as rods or wires is clad by forming a sheath of material different from that of the elements about the bundle. The bundle is subsequently drawn to constrict the elements to a desired small diameter. The elements may be formed of metal. The bundle may be annealed, or stress relieved, between drawing steps as desired. The sheath may be formed of metal and may have juxtaposed edges thereof welded together to retain the assembly. The sheath is removed from the final constricted bundle to free the filaments in the form of tow.
U.S. Pat. No. 4,412,474 to Hara discloses a fiber cord comprising a core that is formed by braiding a plurality of strands, each comprising at least one fiber filament of high elongation. An outer layer element is formed around the core by braiding a plurality of strands, each comprising at least one fiber filament of low elongation and high strength. A protective layer element is formed around the outer layer element by braiding a plurality of strands, each comprising at least one fiber of high elongation.
U.S. Pat. No. 4,514,880 to Vaughn discloses a method and machine for forming nonwoven batts containing refractory fibers such as carbon, glass, ceramic or metallic fibers, includes a conveying table provided with scalloped rollers which separate tows of filaments and spread the filaments on a conveying table. A feed roller holds the filaments on the table so that they are conveyed to a rotating lickerin. The lickerin is provided with teeth that grasp the filaments so that a tensile force is applied thereto, thereby breaking the filaments at structurally weak points in the filaments. The fibers are mixed with textile fibers and transferred to a foraminous condenser by blowing the fibers through a duct. The fibers are arranged on the conveyor in a random fashion to form a batt.
U.S. Pat. No. 4,610,926 to Tezuka discloses a reinforcing steel fiber to be mixed in concrete having a shaft portion that has strength as a mother material. There are on both sides of the shaft portion, alternately formed knots expanding in width become increased in width in the direction towards the ends of the fiber while they become decreased in thickness while knots expanding in thickness extend almost uniformly over the full length.
U.S. Pat. No. 4,677,818 to Honda, deceased et al. discloses a composite rope obtained by a process comprising (1) impregnating a fiber core of a reinforcing fiber bundle with a thermosetting resin, (2) coating the outer periphery of the resin-impregnated fiber core with fibers, and (3) curing the thermosetting resin with heat.
U.S. Pat. No. 4,771,596 to Klein discloses a fine heterogeneous hybrid spun yarn blended from electrostatically conductive staple fibers and electrostatically non-conductive staple fibers so that the yarn is electrostatically conductive only over short discrete lengths. When used in pile fabrics, such as carpets, the fine yarn is introduced with at least some of the carpet facing yarns during the carpet making operations. The resultant carpet structure substantially eliminates electrostatic shock to a human walking across the carpet and approaching a ground such as a light switch, radio and another person. Such a carpet does not constitute a dangerous floor covering. The unique heterogeneous hybrid spun blended yarn is achieved by process techniques completely contrary to accepted blending practices.
U.S. Pat. No. 5,525,423 to Liberman et al. discloses an apparatus and method for an improved fabric having plural diameter metallic wires, comprising the drawing of a first cladded metallic wire to provide a first drawn cladding of reduced diameter. The first cladding is separated into a primary portion and a secondary with the secondary portion being drawn to reduce the diameter. A selected mixture of the primary and the secondary portions are cladded to provide a third cladding of reduced diameter. The third cladding is drawn and the claddings are removed to provide a fabric comprising metallic wires having a major diameter and a minor diameter. The fabric may be severed into uniform length to provide slivers of metallic wires having plural diameters. The plural diameter slivers may be used for various purposes including a filter medium or may be encapsulated within polymeric material for providing an electrically conductive metallic layer therein.
U.S. Pat. No. 5,584,109 to DiGiovanni et al. discloses an improved battery plate and method of making for an electric storage battery. The battery plate comprises a plurality of metallic fibers of a single or plural diameters randomly oriented and sintered to provide a conductive battery plate with a multiplicity of pores defined therein. The metallic fibers are formed by cladding and drawing a plurality of metallic wires to provide the fabric. The fabric is severed and the cladding is removed to form metallic fibers. The metallic fibers are arranged into a web and sintered to form the battery plate.
U.S. Pat. No. 5,630,700 to Olsen et al. discloses a turbine nozzle including outer and inner bands having respective mounting therein. A plurality of vanes extends through respective pairs of outer and inner holes in the bands. The vane outer and inner ends are resiliently supported to the bands to allow differential thermal movement therebetween so that the individual vanes float relative to the outer and inner bands to prevent thermal stress failure thereof.
U.S. Pat. No. 5,707,467 to Matsumaru et al. discloses a high elongation compact helical steel cord with a high degree of elongation at break of not less than 5% has a (1xc3x97n) structure. The steel cord comprises three or more base wires which are helically preformed at a predetermined pitch and that are twisted in the same direction and at the same pitch so that the ratio P/D of the cord diameter D to the twisting pitch P is in the range of 8-15 with the base wire preforming pitch being shorter than the cord twisting pitch. The finished cord has a helical composite structure with its elongation under a load of 35 kgf/mm2 being 0.71%-1.00% and that under a load of 70 kgf/mm2 being 1.18%-1.57%. A radial tire is reinforced with the steel cord preferably as a steel belt cord. An appartaus for making the steel cord is provided with revolving preformers on the wire introducing portion of a bunching machine such that the bunching machine is rotated in a direction reverse to the rotational direction of the revolving preformers.
U.S. Pat. No. 5,722,226 to Matsumaru discloses a steel cord effective for reinforcing a super-large off-road tire wherein strands made by simultaneously twisting together 3 to 6 steel wires in the same twisting direction with the same pitch length. Each of the steel wires consulting the strands continuously has a small wavy pattern of a pitch length smaller than the lay length of the strands and therefore each of the strands has a compound pattern comprising a wavy pattern formed by the twisting. The small wavy pattern and gap is formed between steel wires each of the strands by the small wavy pattern. The lay length P1 of the strands is defined by the small wavy pattern. The lay length P1 of the steel cord is 8 to 15 times the steel cord diameter D and the elongation on breakage by tension of the steel cord is over 5%.
U.S. Pat. No. 5,802,830 to Kawatani discloses that the present invention relates to a steel cord comprising two core wires and five outer wires each having a diameter larger than that of each core wire and integrally twisted on the core wires, wherein a strand constituted by the five outer wires and the two core wires has an oblong cross-section.
U.S. Pat. No. 5,839,264 to Uchio discloses that the steel cord for reinforcement of an off-road tire has a superior resistance to penetration and durability with respect to sharp objects. It has a 3xc3x973, a 3xc3x974, a 4xc3x973 or a 4xc3x974 structure, an identical cord diameter at all points along the steel cord in a longitudinal direction, a cord lay length equal to from 3.5 to 7.5 times the cord diameter and an elongation at break of at least 4%. The steel cord is made up of element wires, each having a wire diameter of from 0.3 to 0.5 mm and a tensile strength of from 2000 to 3300 Mpa.
U.S. Pat. No. 5,888,321 to Kazama et al. discloses steel wire for making steel cord used in rubber product reinforcement has a tensile strength, Y in N/mm2, such that Yxe2x89xa7xe2x88x921960 d+3920, wherein d is the wire diameter in mm, and also a flat Vickers hardness distribution in a cross-section perpendicular to a length direction thereof from the surface to the interior, but excluding a central portion having a central portion diameter corresponding to xc2xc of the wire diameter. The steel wire is made by a method including wet drawing a carbon steel wire rod material containing 0.80 to 0.89% by weight carbon to a predetermined intermediate diameter and subsequently heat-treating and plating to form a final raw material and then wet drawing the final raw material to form the steel wire. The wet drawing steps are performed with drawing dies, each of which is provided with a drawing hole having a drawing hole diameter d1 and the drawing die has an approach angle 2xcex1 equal to from 8xc2x0 to 10xc2x0 and a bearing length of 0.3 d1. The wet drawing of the final raw material includes a final drawing step performed with a double die and the steel wire immediately after passing through the final drawing die has its temperature controlled so as to be less than 150xc2x0 C.
U.S. Pat. No. 5,890,272 to Liberman et al. discloses a process for making fine metallic fibers comprising coating a plurality of metallic wires with a coating material. The plurality of metallic wires are jacketed with a tube for providing a cladding. The cladding is drawn for reducing the outer diameter thereof. The cladding is removed to provide a remainder comprising the coating material with the plurality of metallic wires contained therein. The remainder is drawn for reducing the diameter thereof and for reducing the corresponding diameter of the plurality of metallic wires contained therein. The coating material is removed for providing the plurality of fine metallic fibers.
U.S. Pat. No. 5,956,935 to Katayama et al. discloses that the steel wire is made using a carbon steel wire rod material containing 0.70 to 0.75 wt % carbon and has the characteristics that its diameter is 0.10 to 0.40 mm and Yxe2x89xa7xe2x88x921960 d+3580 [Y: tensile strength (N/mm2), d: diameter (mm)]. Furthermore, the torque decrease factor of the steel wire is less than 7% in a torsion-torque curve in a torsion-torque test wherein forward twisting and then reverse twisting are applied. A preferred steel cord has two steel wires bundled together substantially in parallel and one steel wire is wound around this bundle. This steel cord is made from steel wires having the diameter, tensile strength and toughness characteristics set forth above, and also the ratio B/A of the strength B of the twisted steel cord to the aggregate strength A of the steel wires before they are twisted together into the steel cord is 0.935 or over.
Therefore it is an object of this invention to provide an apparatus and a process for producing high quality metallic mesh from fine metallic threads that eliminates the difficulties in leaching the continuous clad array of metallic fiber tow encountered by the prior art.
Another object of this invention is to provide an apparatus and a process for producing high quality metallic mesh from metallic fiber tow wherein a clad array of metallic fiber tow is formed into a mesh and subsequently is leached to remove the cladding to provide a metallic mesh.
Another object of this invention is to provide an apparatus and a process for producing high quality metallic mesh from a clad array of metallic fiber tow that inhibits the individual fibers of the metallic mesh from being ensnared with adjacent individual metallic fibers of the metallic mesh.
Another object of this invention is to provide an apparatus and a process for producing high quality metallic mesh from high quality metallic tow with minimal broken fibers.
Another object of this invention is to provide an apparatus and a process for producing high quality metallic mesh that is capable of producing high quality metallic mesh in commercial quantities at a reasonable manufacturing cost.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment of the invention.
A specific embodiment of the present invention is shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to the process for making fine metallic mesh, comprising the steps of cladding an array of metallic wires with an array cladding material to provide an array cladding. The array cladding is drawn for reducing the diameter thereof and for reducing the corresponding diameters of each of the metallic wires of the array within the array cladding for providing a drawn array cladding of fine metallic fibers. The drawn array of fine metallic fibers is formed into a metallic mesh thereby creating a series of bends in the drawn array cladding for reducing interaction between adjacent portions of the array cladding. The array cladding material is removed for producing the metallic mesh from the array of fine metallic fibers.
In a more specific example of the invention, the step of cladding the array of metallic wires includes cladding a wire with a wire cladding material to provide a wire cladding. An array of the wire claddings is assembled and the assembled array of wire claddings is clad with the array cladding material to provide an array cladding. In one example of the invention, the step of cladding the metallic wires includes electroplating a wire with a wire cladding material to provide a wire cladding. The step of drawing the array cladding may include a multiple drawing and annealing process for producing a drawn array cladding of fine metallic fibers.
In another more specific example of the invention, the step of forming a series of bends in the drawn array cladding includes forming a series of bends along the longitudinal length of the drawn array cladding. The series of bends may be disposed in one dimension or two dimensions perpendicular to a third dimension extending along the longitudinal length of the drawn array cladding.
Preferably, the series of bends in the array cladding includes a continuous periodic series of curves in the array cladding such as a continuous sinusoidal bend in the drawn array cladding. The series of bends minimizes the direct contact between adjacent portions of the drawn array cladding for minimizing interaction between the array of fine metallic fibers after removal of the array cladding material. Preferably, the array cladding material is chemically removed for providing the metallic mesh formed from an array of fine metallic fibers.
In another example of the invention, the invention is incorporated into the process for making a fine metallic mesh from a multiplicity of metallic threads wherein the metallic threads are formed by drawing the array cladding for reducing the diameter thereof and for reducing the corresponding diameters of each of the metallic wires of the array within the array cladding for producing a drawn array cladding of fine metallic fibers to function as a thread for the fine metallic mesh. The threads of the drawn array of fine metallic fibers are formed into a metallic mesh thereby creating a series of bends in the drawn array cladding for reducing interaction between adjacent portions of the array cladding. The threads may be formed into a metallic mesh by weaving or braiding the threads or any suitable textile process. The array cladding material is removed for producing the metallic mesh from the array of fine metallic fibers.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject matter of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention.